$8cd + 9d + 5e + 3 = -10d + 9e - 1$ Solve for $c$.
Explanation: Combine constant terms on the right. $8cd + 9d + 5e + {3} = -10d + 9e - {1}$ $8cd + 9d + 5e = -10d + 9e - {4}$ Combine $e$ terms on the right. $8cd + 9d + {5e} = -10d + {9e} - 4$ $8cd + 9d = -10d + {4e} - 4$ Combine $d$ terms on the right. $8cd + {9d} = -{10d} + 4e - 4$ $8cd = -{19d} + 4e - 4$ Isolate $c$ ${8}c{d} = -19d + 4e - 4$ $c = \dfrac{ -19d + 4e - 4 }{ {8d} }$